• It is a common ==multisystemic== ==inflammatory== disease that begins more frequently between 20 and 60 years of age and represents the most frequent of all interstitial lung diseases.
• The lungs are almost constantly affected (about 90% of cases) with bilateral pulmonary hilar lymph node involvement and possible simultaneous involvement of the lungs.
• Histopathology features include noncaseating epithelioid granulomas with tightly packed epithelioid cells, Langhans giant cells, and T lymphocytes.

• Lung involvement is commonest - Histology shows increased lymphocytes in alveolar walls and they can also be seen in bonchoalveolar lavage washings.
  • Skin - upto 30% - (lupus pernio, erythema nodosum) and eye -5% - (uveitis) are the commonest.
    • [[Sarcoidosis]] is the commonest cause of erythema nodosum.

[!INFO] Löfgren’s syndrome:
Lofgren's syndrome is an acute form of the disease characterised by:

Sarcoidosis

[!TIP] Summary
Symmetrical Bilateral Hilar lymphadenopathy (BHL) is a characteristic feature of sarcoidosis and is usually asymptomatic.

#sarcoidosis

• It is a common ==multisystemic== ==inflammatory== disease that begins more frequently between 20 and 60 years of age and represents the most frequent of all interstitial lung diseases.
• Commoner in young adults.
• The lungs are almost constantly affected (about 90% of cases) with bilateral pulmonary hilar lymph node involvement and possible simultaneous involvement of the lungs.
• Histopathology features include noncaseating epithelioid granulomas with tightly packed epithelioid cells, Langhans giant cells, and T lymphocytes.
• These findings are localized in interstitium adjacent to bronchioles as well as around and within vessel walls, pleura, and connective tissue septa. There are Schaumann bodies (laminated concretions of calcium and protein) and asteroid elements (stellate inclusions within giant cells).

• Multisystem inflammatory disease
• Etiology unknown.
• Relapses in most people
• Lung involvement is commonest - Histology shows increased lymphocytes in alveolar walls and they can also be seen in bonchoalveolar lavage washings.
• Extracardiac manifestations:
  • Skin - upto 30% - (lupus pernio, erythema nodosum) and eye -5% - (uveitis) are the commonest.
    • [[Sarcoidosis]] is the commonest cause of erythema nodosum.
  • CNS and cardiac are the most important.
• Course of sarcoidosis is unaffected by pregnancy.

[!INFO] Lupus pernio

Lupus pernio = cutaneous sarcoidosis
Lupus vulgaris = cutaneous tuberculosis

Heart can also be involved: Mild to life threatening spectrum.

• Conduction: Heart block and arrhythmias

• Muscle: Heart failure

• Valves: Valvular dysfunction

• simulated infarction

• pericardial disease

• Renal involvement is uncommon but hypercalcemia and hypercalciuria and cause nephrocalcinosis and cause renal failure. Can also cause granulomatous tubulointerstitial nephritis.

• Hypopituitarism

• Hypoadrenalism

• Cranial nerves palsies

• There is also elevated angiotensin converting enzyme levels (which is produced by the granulomas).

• Hypercalcemia, hypercalciuria and elevated alkaline phosphatase.

Clinical features:

• Commonly diagnosed incidentally due to X ray findings.
  • However, pulmonary involvement can cause cough, exertional dyspnoea and chest discomfort.
  • Chest can be clear to auscultation.
  • Advanced stages will cause restrictive lung disease from fibrosis.
• 20% have erythema nodosum.
• Neurosarcoidosis :
  • meningoencephalitis
  • Cranial nerve palsy (esp. bilateral facial nerve palsy)
  • cord lesions

[!INFO] Löfgren’s syndrome:
Lofgren's syndrome is an acute form of the sarcoidosis characterised by

• bilateral hilar lymphadenopathy,
• erythema nodosum,
• arthralgia and
• fever
  Carries an excellent prognosis

[!INFO] Heerfordt's syndrome
Heerfordt's syndrome
A rare subacute form of [[Sarcoidosis]]
(uveoparotid fever) there is parotid enlargement, fever and uveitis secondary to sarcoidosis

Investigations

FBC: Leukopenia and eosinophilia + thrombocytopenia (rare) and Mild NCNC anaemia.
CXR: Bilateral Hilar lymphadenopahty - very common!
Hypercalcemia secondary to increased vitamin D production (macrophages activate a vitamin D precursor)
Renal involvement with elevated creatinine is uncommon

Prognosis

• Stage 1 has very high (upto 90%) rates of spontaneous resolution.
• Rate of resolution decreases rapidly with stage.
• Relapses are common.

Management

• Lung disease can resolve spontaneously and steroids improve radiologic appearance but not always lung function.
  • Therefore, systemic steroids are not regularly used for thoracic sarcoidosis.
• Extrapulmonary sarcoisosis (CNS, Heart, Eye) and hypercalcemia are indications for systemic steroids.

Causes of bilateral hilar lymphadenopathy

[!TIP] Bilateral Hilar lymphadenopathy SCaLP
Causes of bilateral Hilar lymphadenopathy

1. Lymphoma,
2. pulmonary TB,
3. carcinoma of the bronchus,
4. sarcoidosis
   #hilar-Lymphadenopathy #mediastinal-Lymphadenopathy

Differential diagnosis of hilar lymphadenopathy

Clinical context: "non superficial lymph nodes".
(In contrast, enlarged intraabdominal or retroperitoneal nodes are usually malignant.)

Mediastinal lymphadenopathy is caused by primary lung diseases or systemic diseases with predilection for the mediastinal nodes.
Causes:

From Harrison's:

• Young people :

  • Infectious mononucleosis
  • [[Sarcoidosis]]
  • Histoplasmosis - unilateral adenopathy, mimics lymphoma.

• Older people:

  • Primary lung cancer
  • Metastasis
  • Lymphomas
  • [[Tuberculosis]]
  • [[Fungal infections]]
  • [[Sarcoidosis]]

A more comprehensive list from the internet book of critical care:
Source

Calcification of lymph nodes

Granulomatous diseases can cause calcification of lymph nodes.

• TB
• Sarcoisosis
• Silicosis

Calcification is also seen in

• Amyloidosis
• Malignancies

Sarcoidosis

[!TIP] Summary
Symmetrical Bilateral Hilar lymphadenopathy (BHL) is a characteristic feature of sarcoidosis and is usually asymptomatic.

#sarcoidosis

• It is a common ==multisystemic== ==inflammatory== disease that begins more frequently between 20 and 60 years of age and represents the most frequent of all interstitial lung diseases.
• Commoner in young adults.
• The lungs are almost constantly affected (about 90% of cases) with bilateral pulmonary hilar lymph node involvement and possible simultaneous involvement of the lungs.
• Histopathology features include noncaseating epithelioid granulomas with tightly packed epithelioid cells, Langhans giant cells, and T lymphocytes.
• These findings are localized in interstitium adjacent to bronchioles as well as around and within vessel walls, pleura, and connective tissue septa. There are Schaumann bodies (laminated concretions of calcium and protein) and asteroid elements (stellate inclusions within giant cells).

• Multisystem inflammatory disease
• Etiology unknown.
• Relapses in most people
• Lung involvement is commonest - Histology shows increased lymphocytes in alveolar walls and they can also be seen in bonchoalveolar lavage washings.
• Extracardiac manifestations:
  • Skin - upto 30% - (lupus pernio, erythema nodosum) and eye -5% - (uveitis) are the commonest.
    • [[Sarcoidosis]] is the commonest cause of erythema nodosum.
  • CNS and cardiac are the most important.
• Course of sarcoidosis is unaffected by pregnancy.

[!INFO] Lupus pernio

Lupus pernio = cutaneous sarcoidosis
Lupus vulgaris = cutaneous tuberculosis

Heart can also be involved: Mild to life threatening spectrum.

• Conduction: Heart block and arrhythmias

• Muscle: Heart failure

• Valves: Valvular dysfunction

• simulated infarction

• pericardial disease

• Renal involvement is uncommon but hypercalcemia and hypercalciuria and cause nephrocalcinosis and cause renal failure. Can also cause granulomatous tubulointerstitial nephritis.

• Hypopituitarism

• Hypoadrenalism

• Cranial nerves palsies

• There is also elevated angiotensin converting enzyme levels (which is produced by the granulomas).

• Hypercalcemia, hypercalciuria and elevated alkaline phosphatase.

Clinical features:

• Commonly diagnosed incidentally due to X ray findings.
  • However, pulmonary involvement can cause cough, exertional dyspnoea and chest discomfort.
  • Chest can be clear to auscultation.
  • Advanced stages will cause restrictive lung disease from fibrosis.
• 20% have erythema nodosum.
• Neurosarcoidosis :
  • meningoencephalitis
  • Cranial nerve palsy (esp. bilateral facial nerve palsy)
  • cord lesions

[!INFO] Löfgren’s syndrome:
Lofgren's syndrome is an acute form of the sarcoidosis characterised by

• bilateral hilar lymphadenopathy,
• erythema nodosum,
• arthralgia and
• fever
  Carries an excellent prognosis

[!INFO] Heerfordt's syndrome
Heerfordt's syndrome
A rare subacute form of [[Sarcoidosis]]
(uveoparotid fever) there is parotid enlargement, fever and uveitis secondary to sarcoidosis

Investigations

FBC: Leukopenia and eosinophilia + thrombocytopenia (rare) and Mild NCNC anaemia.
CXR: Bilateral Hilar lymphadenopahty - very common!
Hypercalcemia secondary to increased vitamin D production (macrophages activate a vitamin D precursor)
Renal involvement with elevated creatinine is uncommon

Prognosis

• Stage 1 has very high (upto 90%) rates of spontaneous resolution.
• Rate of resolution decreases rapidly with stage.
• Relapses are common.

Management

• Lung disease can resolve spontaneously and steroids improve radiologic appearance but not always lung function.
  • Therefore, systemic steroids are not regularly used for thoracic sarcoidosis.
• Extrapulmonary sarcoisosis (CNS, Heart, Eye) and hypercalcemia are indications for systemic steroids.

Causes of bilateral hilar lymphadenopathy

[!TIP] Bilateral Hilar lymphadenopathy SCaLP
Causes of bilateral Hilar lymphadenopathy

1. Lymphoma,
2. pulmonary TB,
3. carcinoma of the bronchus,
4. sarcoidosis
   #hilar-Lymphadenopathy #mediastinal-Lymphadenopathy

Differential diagnosis of hilar lymphadenopathy

Clinical context: "non superficial lymph nodes".
(In contrast, enlarged intraabdominal or retroperitoneal nodes are usually malignant.)

Mediastinal lymphadenopathy is caused by primary lung diseases or systemic diseases with predilection for the mediastinal nodes.
Causes:

From Harrison's:

• Young people :

  • Infectious mononucleosis
  • [[Sarcoidosis]]
  • Histoplasmosis - unilateral adenopathy, mimics lymphoma.

• Older people:

  • Primary lung cancer
  • Metastasis
  • Lymphomas
  • [[Tuberculosis]]
  • [[Fungal infections]]
  • [[Sarcoidosis]]

A more comprehensive list from the internet book of critical care:
Source

Calcification of lymph nodes

Granulomatous diseases can cause calcification of lymph nodes.

• TB
• Sarcoisosis
• Silicosis

Calcification is also seen in

• Amyloidosis
• Malignancies

" MesPGN may occur in several renal diseases such as IgA nephropathy (commonly), IgM nephropathy, lupus nephritis, and C1q nephropathy". Source

one and a half syndrome

(A) Pathologic lesion (oval shaded area) in the dorsal pontine tegmentum involves both ipsilateral PPRF (or the abducens nucleus) and the ipsilateral MLF; (B) Position of eyeballs, with rightward gaze, the left eye has the impaired adduction, while the abduction of the right eye is intact, except for the nystagmus, and with left gaze, both eyes have impaired horizontal movement (abduction of the left eye and adduction of right eye).

Source

• Caused by fungus; histoplasma capsulatum.
• Mycelium is the infective stage.
• Found in soil nourished with bird droppings.
• Disturbance of soil leads to aerosolization of microconidia which then infect humans upon inhalation.
• Exposures increasing risk : spelunking, logging, demolition of old building.
• They are engulved by marcophages; Inside macrophages, the hyphae become the yeast form.
• Using the macrophages, the disseminate to the mediastinal lymph nodes and the rest of the reticuloendothelial system.
• In immunocompetent hosts, infection is mild or asymptomatic. The immune system develops cell mediated immunity and arrests spread of the fungus by forming granulomas which calcify. (calfied lesions are seen in healthy people from endemic areas.)
• Symptoms: Fever, chills, fatigue,
• In immunocompromised patients, disseminated infection can occur.
• Illness can range from mild to life threatening.
• Diagnosis: histoplasma antigen test.
• Treatment: mild cases - itraconazole; others - liposomal amphotericin B.